Following reports that the Federal Bureau of Investigation (FBI) used at least one spy to secretly surveil members of the Trump campaign, fired former FBI director James Comey lashed out at critics of his agency’s activities during the 2016 election.

“Facts matter. The FBI’s use of Confidential Human Sources (the actual term) is tightly regulated and essential to protecting the country,” Comey tweeted on May 23. “Attacks on the FBI and lying about its work will do lasting damage to our country.”

While Comey’s record on truth-telling is decidedlymixed, he is correct that facts matter and that the FBI’s use of informants is governed by strict guidelines. How and why many of those guidelines came to be are important facts that the American public deserves to know as it considers revelations that the FBI used wiretaps and spies to surveil Donald Trump’s presidential campaign, his transition, and perhaps even his presidential administration.

Those guidelines, many of which the Government Accountability Office found were not being followed as recently as 2015, were put in place after rogue FBI agents working in the Boston field office routinely worked to cover up murders committed by their informants. You might say they were the direct result of justifiable attacks on the FBI for unconscionable violations of the public trust.

The 2007 ruling from U.S. District Court Judge Gertner, which the federal government chose not to appeal, reads more like a John Grisham novel than it does a legal dictum. In her introduction, Gertner made clear that the horrific miscarriage of justice perpetrated under the guise of the FBI’s confidential spy program wasn’t the result of innocent missteps by a few bad apples, but was instead a coordinated conspiracy involving the rogue agents, their supervisors, and even the FBI director himself.

The corrupt agents were “given raises and promotions precisely for their extraordinary role in procuring” the wrongful convictions, Gertner wrote.

“Even when [their informant], the ‘poster boy’ for the new federal witness protection program, committed yet another murder, three federal officials testified — now for the second time — on his behalf,” noted Gertner. “FBI officials up the line allowed their employees to break laws, violate rules and ruin lives, interrupted only with the occasional burst of applause.”

“When [three of the wrongfully convicted men] were sentenced to death,” Gertner wrote, “the FBI did not stand silently; they congratulated the agents for a job well done.”

As detailed in a 2003 congressional report detailing the widespread and deliberate FBI corruption surrounding its confidential informant program, one agent who was directly involved in the conspiracy to frame four innocents was not just unapologetic, he was defiant.

When a congressional panel conducting an investigation into the FBI’s handling of the original criminal case and its aftermath asked the agent if he felt remorse for what happened, he all but openly mocked the idea.

“Would you like tears or something?” the agent shot back. “I believe the FBI handled it properly.”

The elected lawmakers who investigated the FBI and later compiled a lengthy report on what happened didn’t expect anyone to pore through all 3,500 pages, so they subtly summarized their findings via the name of their report: “EVERYTHING SECRET DEGENERATES: THE FBI’S USE OF MURDERERS AS INFORMANTS.”

Since then, the FBI and DOJ have reformed the bureau’s guidelines in hopes of avoiding another scandal like the one in Boston. But its shadow still lingers. A 2005 report from the DOJ inspector general found widespread violations of DOJ’s confidential informant guidelines by the FBI, which was then headed by Robert Mueller, who now serves as a special counsel investigating illegal foreign interference in the 2016 U.S. presidential election.

“We found significant problems in the FBI’s compliance with Guidelines’ provisions,” the inspector general’s report noted. The report specifically called out the FBI’s failure to properly document its explicit approval of illegal activities by its informants.

“In total, we found one or more Guidelines compliance errors in 87 percent of the informant files we examined,” the investigation concluded.

The inspector general wrote that the FBI’s failure to comply with basic guidelines governing the use of confidential informants was especially troubling given the FBI’s history in Boston. The report provided 47 separate recommendations to the FBI to improve its compliance with DOJ’s spy guidelines.

The most chilling finding by the inspector general was that informants were authorized to engage in illegal activity even when the FBI hadn’t yet fully vetted and registered them as confidential informants. In one instance, the FBI authorized one of its informants to commit robbery, a violent crime, despite the fact that such activity is expressly forbidden by DOJ’s guidelines.

In mid-2006, the issue of FBI spy abuse still had enough resonance that Sen. Patrick Leahy (D-Vt.), who at the time served as the chairman of the Senate Judiciary Committee, required then-Attorney General Alberto Gonzales to answer detailed questions about his agency’s guidelines for and oversight of the FBI’s confidential spy program.

“We now know that there were over twenty murders by [FBI] informants in Massachusetts, and the FBI never told state and local law enforcement what it knew,” Leahy wrote. “On your watch, what steps are you taking to ensure that past misuse of confidential informants will not happen again? What safeguards in place to prevent abuses from occurring?”

In her ruling excoriating the federal government for its willful perversion of justice through its use of confidential informants, federal judge Nancy Gertner forcefully tossed aside the idea, glibly offered by Comey and many of his defenders, that oversight of the FBI and transparency surrounding its activities and behavior somehow constitute a malicious attack on justice or democracy. To the contrary, Gertner noted that abuse by law enforcement officials was especially damaging because so much of our justice system depends on a collective trust in the ability of law enforcement officials, many of whom by necessity must operate in the dark, to be honest and forthright.

“Sadly, when law enforcement perverts its mission, the criminal justice system does not easily self-correct,” she wrote. “While judges are scrutinized — our decisions made in public and appealed — law enforcement decisions like these rarely see the light of day. The public necessarily relies on the integrity and professionalism of its officials. It took nearly thirty years to uncover this injustice. It took the extraordinary efforts of a judge, a lawyer, even a reporter, to finally bring out the facts.”

“Proof of innocence in this democracy should not depend upon efforts as gargantuan as these.”

As James Comey said, facts matter. And given what we know about the FBI’s history with secret spies, facts matter especially when the FBI decides the public doesn’t deserve to know them.